This invention relates to equipment used in optical systems for examining liquid specimens, and relates more particularly to an improved transparent laboratory slide having at least one chamber for holding the specimen as it is subjected to optical examination.
Transparent laboratory slides for containing a liquid specimen to be examined, such as a body fluid, are disclosed in U.S. Pat. No. 3,777,283 issued to Elkins (commonly assigned). The structure of the Elkins slide permits capillary action to charge a liquid specimen introduced onto the slide into an examination chamber. Moreover, such capillary action acts to retain the specimen in the chamber. The specimen can then be visually inspected and the occurrence of certain suspended materials in a given unit volume can be quantitatively and qualitatively evaluated. The results of these evaluations may then be extrapolated to determine the given characteristics of the entire sample extracted from a patient and thereby provide a valuable diagnostic tool in detection of a variety of diseases.
It is desirable, if not necessary, to have the chamber wall of the slide as thin as possible to achieve rapid focusing under microscope examination and to have the chamber as small as possible but still contain a representative portion of the sample so that the laboratory technician need only examine a small quantity of the sample for a specific evaluation and preserve the remainder for additional testing.
Fabrication of slides having a small, yet accurately configured chambers and chamber sidewalls in machines capable of mass production presents certain difficulties. As the chamber size is reduced, slight manufacturing inaccuracies become increasingly significant, in percentage terms, as such inaccuracies may adversely affect the desired chamber volume and desired quantity of specimen contained therein. Moreover, as molded parts of the slide decrease in size, the molten plastic is increasingly likely to chill and harden prematurely in the mold, before the molding process is fully completed. Additionally, disruptions in precise molding may also be caused by trapped gases within the mold and thereby pose problems regarding accurate construction of the slide within given design tolerances.
Certain parameters must be met for selection of suitable materials from which the slide is composed. For instance, should the material react chemically with or have significant affinity for agents present in the contained specimen, the accuracy and reproducibility of the evaluation may be deleteriously affected. Certain materials from which slide can be fabricated may cause packaged multiple slides to adhere to one another which may cause scratching or marring of the slide surface and resultant difficulties in performing accurate microscopic examination of the specimen. Additionally, such affinity of slides for one another makes separation of packaged multiple slides difficult and time consuming.
Hence, those concerned with structural characteristics and fabrication of transparent slides for examination of liquid specimens have recognized a significant need for an improved slide having a smaller examination chamber fabricated by a process which insures the accuracy of its manufacture within given parameters and which overcomes the foregoing difficulties. The present invention fulfills this need.